C320 / C350 CDI 3.0 V6 (OM642)
2007–2014 · diesel · 2987cc · 224hp
Engine codes: OM642
Reliability, common problems and owner reviews for the Mercedes Benz C-Class W204 C320 / C350 CDI 3.0 V6 (OM642). Check this before you buy used.
The 3.0 V6 diesel — strong and refined with a tough bottom end, but it has signature ancillary issues: the oil cooler seals leak (common, labour-heavy) and the intake swirl flaps/runners (the 'Saugrohr' assembly) wear. Excellent when these are sorted; budget for them otherwise.
Same engine, other cars
This is the same physical engine (OM642) sold under different names across brands. Reliability is broadly shared — cross-check these:
- Mercedes-Benz GLK— 320/350 CDI 3.0 V6 (OM642)224hp
- Mercedes-Benz Vito / Viano— 3.0 CDI V6 (OM642)224hp
- Jeep Grand Cherokee— 3.0 CRD V6 (OM642, Mercedes)218hp
- Mercedes-Benz M-Class (ML)— ML350 CDI 3.0 V6 (OM642)258hp
- Mercedes-Benz E-Class W211— E280 / E320 CDI 3.0 V6 (OM642)224hp
- Mercedes-Benz M-Class (ML)— ML280/320/350 CDI 3.0 V6 (OM642)224hp
Known Issues
Oil cooler seals (between the V) leak oil onto the engine — common OM642 issue, labour-intensive to fix.
Fix / Workaround: Replace oil cooler seals (updated parts).
Repair cost: €500–€1200
Typically appears after: 120,000 km
Intake manifold swirl flaps/linkage wear and can be ingested.
Fix / Workaround: Replace/delete intake runner assembly.
Repair cost: €300–€900
Mileage Thresholds
After 150,000 km: Oil cooler / intake attention typically due.
Pre-Purchase Checklist
- ☐Inspect for oil cooler seal leaks
- ☐Ask about intake swirl flap/runner condition
- ☐Strong engine once these are done
Frequently asked questions
Is the Mercedes Benz C-Class W204 C320 / C350 CDI 3.0 V6 (OM642) reliable?
Maint. Sensitive — The 3.0 V6 diesel — strong and refined with a tough bottom end, but it has signature ancillary issues: the oil cooler seals leak (common, labour-heavy) and the intake swirl flaps/runners (the 'Saugrohr' assembly) wear. Excellent when these are sorted; budget for them otherwise.
What are the common problems and reviews for the Mercedes Benz C-Class W204 C320 / C350 CDI 3.0 V6 (OM642)?
The most commonly reported problems: Oil cooler seal leak, Intake swirl flap / runner wear.
Is a used Mercedes Benz C-Class W204 C320 / C350 CDI 3.0 V6 (OM642) worth buying?
Fine if serviced correctly — but it punishes neglect hard. History and the right consumables matter.